The present invention relates to a composition of matter and more particularly it relates to a mixture of dialkyl ethers of polyalkylene glycols useful in removing acidic gas components such as hydrogen sulfide from gas mixtures. Still more particularly the present invention relates to a mixture of dimethyl ethers of polyethylene glycol, having an average molecular weight of from about 200 to 255, and preferably from 227 to 244, which is effective at low temperatures for the removal of acidic gas components from gas mixtures.
U.S. Pat. No. 3,737,392 teaches that a certain mixture of dimethyl ethers of polyethylene glycols is useful in treating and separating acid gas particularly hydrogen sulfide from gas mixtures such as natural gas mixtures containing hydrogen sulfide, carbon dioxide and methane. Such a solvent system available under the trademark SELEXOL has been widely and successfully used in many natural gas treating operations.
However, it has been found that such a solvent system does not operate efficiently at subfreezing temperatures. Thus, for example, at about 10.degree. F. to about -10.degree. F. the solvent rapidly becomes rather viscous. The increased viscosity tends to reduce the rate of solvent flow through a gas absorber so that less and less gas can be treated. Further at this low temperature the solvent starts to freeze, fouling heat exchangers. Then mass transfer problems begin to appear further reducing the efficiency of the gas treating operation. The solvent according to the present invention markedly alleviates and in some instances completely eliminates these problems.